Chassis supported track assembly

ABSTRACT

An endless track assembly wherein the weight of an associated vehicle/equipment is supported by the track framework. The track assembly provides a framework having a number of idler rollers and a drive sprocket that mounts to a rotational drive power source. The weight of the vehicle is transferred from a vehicle/equipment support flange that cooperates with a complementary support surface of the track framework and an intermediate bearing liner. The bearing support surfaces cooperate to permit the track frame to pivot relative to the chassis independent of the drive sprocket. The track assembly is particularly adapted to pivoting irrigation systems.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation of application Ser. No. 10/659,672, filed on Sep.10, 2003, now U.S. Pat. No. 6,926,105.

BACKGROUND OF THE INVENTION

The present invention relates to a track assembly and, in particular, toan improved endless track assembly that rotationally couples to avehicle drive power source and pivotally couples to a chassis supportand whereby the chassis support accommodates heavy weight vehicles andambulatory equipment.

Track systems have been developed for use over soft and unpreparednatural terrain by a variety of vehicles and equipment in differentrecreational, commercial, farm and military applications. Such vehiclesand equipment can include wheels and/or endless track assemblies toachieve traction over off-road surfaces with relatively low surfacepressure at the contact surfaces of the drive train. For example, largecapacity people haulers, trailers, manure spreaders, irrigation systems,and military vehicles include tracks. Many devices use tracks thatextend a substantial length of the equipment and are supported by asingle drive roller and/or numerous idler rollers. The vehicle/equipmentweight is generally concentrated at the several axle-bearing surfacesthat extend from the vehicle/equipment. That is, the vehicle weight issupported at the relatively small surface area of several drive trainaxles, while the loading relative to the ground is determined at thelarger surface area of the track to ground interface.

The difficulty with such axle support assemblies is that thechassis/equipment weight is supported by one or more bearing supportshaving relatively small surface areas. The weight of many types ofvehicles and equipment however can exceed the loading tolerances of thebearing surfaces, unless more expensive bearing supports are used.Alternatively, a large number of less costly bearing supports can bedesigned into any piece of equipment.

Desirably a mounting is required whereby a bearing support with a largesurface area is mounted intermediate the chassis of thevehicle/equipment to off-load the primary weight from the bearings ofthe drive/idler axles. The present improved track assembly was developedto accommodate the foregoing need and provide a track assembly whereinthe vehicle weight is supported at a chassis to track assembly bearingsurface.

The improved track assembly provides a framework having a number ofidler rollers that extend from and are displaced along a track frame tosupport an endless track. A separate drive sprocket/drum mounts to arotational drive power source at the vehicle/equipment and controlstrack movement. The weight of the vehicle is supported by a flange thatextends from the chassis and cooperates with a complementary surface ofthe track framework. An intermediate bearing liner mounts between theflange and track framework. The bearing support surface of the trackframework allows the track frame to pivot relative to the chassisindependent of the drive sprocket/drum and/or idler wheels.

SUMMARY OF THE INVENTION

It is a primary object of the invention to provide a large bearingsupport surface area for an endless track framework assembly independentof support surfaces provided at drive and/or idler axles.

It is further object of the invention to provide an endless trackframework having a drive power sprocket/drum and several idler wheelsthat extend and rotate at the framework independent of a frameworkbearing support that mounts between the vehicle/equipment chassis andthe track framework.

It is a further object of the invention to provide a track frameworkhaving a circular bearing support surface that interlocks with acircular chassis support surface and an intermediate bearing liner, suchas constructed from a slippery, high-density material, roller, ball orother bearings.

It is a further object of the invention to provide a resilient,torsional bias between the mating bearing surfaces to resist motion inone or both directions of a reciprocating relative movement between thebearing supports.

It is a further object of the invention to provide mating bearingsurfaces between the vehicle/equipment chassis and a track frameworkwith a resilient, torsion bias and which bearing surfaces areconcentrically aligned to a drive power axle to the track assembly.

The foregoing objects, advantages and distinctions of the invention areobtained in the presently preferred track assembly of the invention. Theassembly provides a metal support framework having a circular bearingsupport surface. Several vertical risers and cross supports of the trackframework brace the bearing support surface. Several sets of largeand/or small diameter idler wheels are arrayed about the framework andmate with an endless drive track. A replaceable drive sprocket/drum iscoupled to a rotary power source at the chassis/equipment and couples torotate the drive track.

A bearing support flange extends from the vehicle/equipment chassis andaligns with the framework bearing support surface. A slippery, highdensity bearing material interfaces between the bearing supportsurfaces. The track framework is thereby supported to rotate relative tovehicle/equipment chassis independent of the rotary drive power sourceto the track assembly.

Resilient members are fitted to the bearing supports to provide atorsional control over reciprocating movement of the track assembly.Springs, expansible/compressible material, hydraulic/pneumaticcylinders, among other resilient mechanisms can be used to provide thedesired torsion control. Stop limits are provided to limit the range ofmotion of the track assembly and/or relative movement of the bearingsupport surfaces.

Still other objects, advantages, distinctions and constructions of theinvention will become more apparent from the following description withrespect to the appended drawings. Similar components and assemblies arereferred to in the various drawings with similar alphanumeric referencecharacters. The description should not be literally construed inlimitation of the invention. Rather, the invention should be interpretedwithin the broad scope of the further appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an assembled perspective drawing of a track assembly whereinthe framework includes a chassis bearing support and wherein the trackis shown in partial section.

FIG. 2 is a perspective drawing of a track assembly wherein theframework and chassis bearing supports are shown in exploded assemblyrelative to the drive sprocket/drum and equipment power take-off.

FIG. 3 is a perspective drawing of a track assembly wherein theframework and chassis bearing supports are shown in exploded assemblyrelative to the drive sprocket/drum and equipment power take-off head,which includes a variable drive ratio gear assembly.

FIG. 4 is a perspective drawing of a track assembly wherein theframework and chassis bearing supports are shown in exploded assemblyrelative to the drive sprocket/drum and an alternative equipment powertake-off.

FIG. 5 is a diagrammatic representation showing resilient biasingmembers supported in a neutral condition between end stops at thechassis and track framework bearing supports.

FIG. 6 is a diagrammatic representation showing the track assemblyrotated against one of the stops with one torsion member compressed andthe other extended to bias the support back to the neutral condition.

Similar structure throughout the drawings is referred to with the samealphanumeric reference numerals and/or characters.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIGS. 1–4, several assembled and exploded assembly viewsare shown to improved track assemblies 2, 4 and 6 of the invention. Thetrack assemblies 2, 4 and 6 find particular use with relatively heavyweight vehicles and equipment, such as large trucks, irrigation systemsand the like. Each of the track assemblies 2, 4 and 6 includes a loadbearing support assembly 10, 12 or 13 that displaces the weight of theassociated vehicle/equipment over a large bearing surface area. Theweight of the vehicle/equipment is thereby shifted off the drive powercoupling and track drive sprocket 14 onto the chassis support assembly10, 12 or 13. The load bearing support assemblies 10, 12 or 13 areconcentrically arranged to the axis of the drive power linkage to allowthe track assemblies 2, 4 and 6 to rotate and accommodate changes in theterrain.

Each of the track assemblies 2, 4 and 6 includes a reinforced, endlesstrack 16, shown only at FIG. 1 but understood to be included with eachof the assemblies 2, 4 and 6. The track 16 is typically constructed ofrubber with suitable belting and reinforcing fibers to withstandtypically encountered terrain, including rocks, logs, mud, sand etc. Theinterior surface of the track 16 provides several laterally displacedrows of lugs 18 that engage lateral teeth 20 of the sprocket 14. Theground-engaging surface 22 of the track 16 includes other lugs 24 thatare shaped and arrayed to enhance traction and travel over ananticipated terrain.

The lateral edges of the track 16 are typically constructed to cup orflex slightly inward at the extreme peripheral edges, upon setting apreferred tension. The cupping in the space adjacent exposed sides ofadjoining idler wheels 28–32 facilitates retention of the track 16 tothe idler wheel suspension.

The track 16 is suspended around the drive sprocket 14 and a framework26. Two large diameter, forward and aft idler wheels 28 and 30 andseveral smaller diameter interior idler wheels 32 support the track 16.The idler wheels 28–32 are supported from axles (not shown) that extendfrom and to the lateral sides of the track framework 26. The idler wheelaxles project from the framework 26 as stationary stub axles. In athrough-frame configuration, they can support a pair of the idler wheels28, 30.

A track tensioner assembly of conventional screw-follower construction(not shown) can be provided to cooperate with the fore and/or aft idlerwheels 28 and 30. Typically such assemblies incorporate a threadedmember that cooperates with a track engaging piece to cause the track 16to expand and contract in relation to the adjustment of the threadedmember.

Alternatively, an eccentric coupling can be provided at the sprocket 14or at the axles to the idler wheels 28 and 30. If such a coupling isprovided between the framework 26 and the drive linkage to thevehicle/equipment, the sprocket 14 is mounted to rotate in a cam fashionrelative to the track 16 to establish the tension. That is, a bearinghousing having and eccentric outer surface is fitted over a drive axleto the sprocket 14 and is aligned to the rotational axis of the sprocket14. A similar mounting of an eccentric housing in the bores of the setsof idler wheels 28, 30 relative to a through axle at either or both ofthe fore and aft idler wheels 28, 30 can cause the sets of idlers wheels28, 30 to expand and contract relative to the track 16. Rotation of thehousing within the bore of the sprocket 14 or idler wheels 28,30 causesthe sprocket 14 or idler wheels 28,30 to rotate toward and away from thetrack 16. In all of the present track assemblies 2, 4 and 6, the tracktension is maintained independent of the mounting of the trackassemblies 2, 4 and 6 to the vehicle/equipment.

The idler wheels 28–32, which are shown in generalized forms, can beconstructed to any desired size from any suitable material to supportthe intended application and loading at the track 16. The wheels 28–32should also be constructed to alleviate any abrasion with the interiorsurface of the track 16. The configuration of the hub, spokes etc. ofeach idler wheel 28–32 can also be varied to the application. The wheels28–32 are also constructed to be relatively intolerant to the adhesionof debris and to promote the discharge of debris from the wheels 28–32and the track interior. The idler wheels 28–32 are aligned at theframework 26 to run in longitudinal channels between the lugs 18 at theinterior surface of the track 16.

The forward and/or aft idler wheels 28 and 30 can also be secured to theframework 26 to permit an independent, resiliently biased rotation ofthe wheels 28, 30 relative to the framework 26. An example of such abiasing assembly is disclosed at applicant's co-pending application Ser.No. 10/348,156. In such a track assembly, the idler wheels 28 and 30 aremounted to rotate and pivot about the framework 26 subject to acontinuous, resilient bias, such as established by a resilient member(e.g. spring, compressible elastomer or expansible member etc.) securedbetween the wheels 28 and/or 30 and/or intermediate linkage to thewheels and the framework 26. The deformation/expansion/contraction ofthe resilient member might also be made adjustable to permit the settingof a preferred bias.

The drive wheel, drum or sprocket 14 is presently constructed of castaluminum, although can be constructed of other materials to accommodatethe loading. Lateral teeth 20 extend between inner and outer annularbands 34 and 36 to engage the leading surfaces of the lugs 18 at thedrive track 16. A multi-spoke hub 38 is secured to a drive power linkageto the vehicle/equipment that supplies drive power to the trackassemblies 2, 4 and 6. The outer peripheral edges of the drive sprocket14 are also shaped to prevent the buildup of debris between the drivesprocket 14 and track 16.

The track assemblies 2, 4 and 6 can be secured to a variety of differentdrive power couplings or linkages. FIG. 2 shows a motor housing 70, suchas provided at a pivoting irrigation assembly (not shown), and asprocket 72 that mate with the hub 38 and drum 14. Drive power isdirectly provided from a drive shaft of the motor 70. For a self-poweredvehicle, power is typically applied from an axle to a driven wheel.

FIG. 3 shows an alternative drive coupling wherein drive power issupplied from a sprocket 76 that is secured to a drive shaft (not shown)that rotates within a shaft housing 78 that extends from theequipment/vehicle. A flange 80 secured to the shaft housing 78 isconfigured to mount to a flange 82 of a chassis support plate 84.Separately mounted to the equipment/vehicle chassis at a mounting plate86 is a geared transfer case 88. A drive shaft 90 and sprocket 92 extendfrom the case 88 and separately attach to the hub 38 to vary therotational drive speed at the shaft 90.

Alternatively, it is to be appreciated that the flange 80 might bemounted to the plate 86. In this instance, the drive power might besupplied from a motor (not shown) or the adjacent vehicle/equipmentdirectly through the transfer case 88 via the single shaft 90. In thisinstance the shaft housing 78 et al. would not be required.

FIG. 4 shows yet another drive coupling wherein a vehicle/equipmentsteering housing 94 supports a drive shaft (not shown) and sprocket 96that mates to the hub 38 and drum 14. Flanges 98 extend from the housing94 and couple to a vehicle/equipment chassis support plate 100. Theflanges 98 particularly attach to offset flanges 102 and 104 at thechassis support plate 100. More of the details to the novel significanceof the chassis support plates 48, 84 and 100 are discussed below.

The framework 26 generally includes a longitudinal section 40 thatsupports the idler wheels 28–32. Riser sections 42 and 44 project fromthe section 40 and mount to a curved or arcuate bearing support plate46. A stationary chassis plate 48 extends from the vehicle/equipment andthe plate 46 is arranged to interact with and rotate relative to theplate 48. The chassis plate 48 is typically mounted to thevehicle/equipment at a flange 50. Slots 52 are formed into the plate 48and fasteners 54 extend between the bearing plates 46 and 48. The weightof the vehicle/equipment is thereby transferred to the bearing supportplates 46 and 48 and the track framework 26, which relieves loading atthe coupling to the drive sprocket 14 or other axle surfaces.

Returning attention to FIG. 2, the track framework 26 is free to rotateto and fro along the chassis support plate 48, limited by the fasteners54 and slots 52, independent of the rotation of the drive coupling tothe sprocket 14. A layer of bushing material or a bearing surface 56 isfitted between the plates 46 and 48 to facilitate relative movement. Thebearing 56 can be constructed of a variety of commercially available,slippery materials, for example high density nylon, oil lite brass orUHMW plastic. Ball and/or roller bearings might also be includedat/between the plates 46 and 48 to promote free relative movement andwhereby the track assemblies 2, 4 and 6 can rotate relative to thevehicle/equipment chassis with terrain changes.

FIGS. 5 and 6 separately depict in diagrammatic form two generalizedconditions wherein the plates 46 and 48 are biased at opposite endsrelative to one another. A torsion suspension is provided to oppose andcontrol relative movement of the track assemblies 2, 4 and 6 to thevehicle/equipment and in relation to a neutral center position. Movementof the plate 46 to either side of a central position is particularlyopposed by at least one biasing member that resiliently operates todirect the member back to the neutral position.

The depicted torsion control provides for the placement of two resilientbias members 58 at or between opposing end flanges 60 and 62 at themoveable track support plate 46 and stationary chassis support plate 48.FIG. 5 depicts a neutral condition, wherein the expansion/contraction ofthe members 58 are balanced. FIG. 6 depicts a limit condition whereinone member 58 is fully extended and the other is fully compressed. Theextended member 58 seeks to pull the moveable plate 46 back to centerand the compressed member 58 seeks to push the plate 46 to the center.The bias members 58 can comprise springs, hydraulic or pneumaticcylinders, elastomers or any other material, device or assembly thatprovides a resilient, push-pull operation relative to the chassis andtrack support plates. It is to be appreciated also that the positioningof the bias members can be varied relative to the chassis support plates48, 84 and 100 relative to the track support plate 46.

While the invention has been described with respect to a number ofpreferred constructions and considered improvements or alternativesthereto, still other constructions may be suggested to those skilled inthe art. It is also to be appreciated that selected ones of theforegoing features can be used singularly or can be arranged indifferent combinations to provide a variety of other improved trackassemblies. The foregoing description should therefore be construed toinclude all those embodiments within the spirit and scope of thefollowing claims.

1. A track assembly for conveying a mobile device comprising: a) aframework including a plurality of idler wheels and a first platesecured to said framework b) a drive power source coupled to saidframework; c) an endless track trained around said plurality of idlerwheels; and d) a second plate mounted to a chassis of said device andaligned to cooperate with said first plate such that said first andsecond plates move on one another, whereby said framework supports theweight of said device as said track assembly rotates relative to saiddevice.
 2. A track assembly as set forth in claim 1 including bearingmeans fitted between said first and second plates to facilitate relativemotion.
 3. A track assembly as set forth in claim 1 including a slipperybearing material fitted between said first and second plates.
 4. A trackassembly as set forth in claim 1 including a plurality of bearingsfitted between said first and second plates.
 5. A track assembly as setforth in claim 1 wherein said first and second plates exhibit arcuatemating surfaces.
 6. A track assembly as set forth in claim 1 whereinsaid first and second plates are resiliently biased relative to oneanother for reciprocating motion between first and second limitpositions.
 7. A track assembly as set forth in claim 6 wherein saidfirst and second plates are resiliently biased to a neutral positionbetween said first and second limit positions.
 8. A track assembly asset forth in claim 6 wherein a compressible member is fitted betweensaid first and second plates.
 9. A track assembly as set forth in claim1 wherein one of said first and second plates includes a slot andwherein a stop member is arranged relative to said slot to limitrotation of said first and second plates relative to one another.
 10. Atrack assembly for conveying a mobile device comprising: a) a frameworkincluding a plurality of rotatively mounted idler wheels, and a firstplate secured to said framework; b) a drive power source coupled to saidframework; c) an endless track trained around said framework; and d) asecond plate mounted to a chassis of said device and aligned tocooperate with said first plate such that said first and second platesmove on one another, whereby said framework supports the weight of saiddevice as said track rotates relative to said device.
 11. A trackassembly as set forth in claim 10 wherein said first and second platesare resiliently biased relative to one another for reciprocating motionbetween first and second limit positions.
 12. A track assembly as setforth in claim 10 including a slippery bearing material fitted betweensaid first and second plates.
 13. A track assembly as set forth in claim10 wherein said first and second plates exhibit arcuate mating surfaces.14. A track assembly for conveying a mobile device comprising: a) aframework including a plurality of rotatively mounted idler wheels, anda first plate secured to said framework; b) an endless track trainedaround said plurality of idler wheels; and c) a second plate mounted toa chassis of said device and aligned to cooperate with said first platesuch that said first and second plates move on one another, whereby saidframework supports the weight of said device as said track rotatesrelative to said device.
 15. A track assembly as set forth in claim 14wherein said first and second plates are biased relative to one anotherfor reciprocating motion between first and second limit positions.
 16. Atrack assembly as set forth in claim 14 including a stop member arrangedto limit rotation of said first and second plates relative to oneanother.
 17. A track assembly as set forth in claim 14 including bearingmeans fitted between said first and second plates to facilitate relativemotion.
 18. A track assembly as set forth in claim 14 including aslippery bearing material fitted between said first and second plates.19. A track assembly as set forth in claim 14 wherein said first andsecond plates exhibit arcuate mating surfaces.
 20. A track assembly asset forth in claim 14 including a drive sprocket coupled to saidframework to rotate said track.
 21. A track assembly for conveying amobile device comprising: a) a framework including a plurality ofrotatively mounted idler wheels, and a first planar member secured tosaid framework; b) an endless track trained around said plurality ofidler wheels; and c) a second planar member mounted to a chassis of saiddevice and aligned to cooperate with said first planar member such thatsaid first and second planar members move on one another, whereby saidframework supports the weight of said device as said track rotatesrelative to said device.